In order to study the effects of augmenting central dopamine activity on brain function and "negative" or "deficit" symptoms in patients with schizophrenia, we have designed a double-blind placebo-controlled crossover trial of combined L-Dopa and molindone or haloperidol, lasting 16 weeks. Throughout the study patients will receive daily BPRS ratings, and twice weekly NSRS and AIMS ratings. At equivalent times during the active and placebo periods patients will undergo measurements of serum prolactin and growth hormone levels, lumbar puncture, computerized brain electrical activity measurement, and cerebral blood flow measurement either by SPECT or 2D rCBF.